Cells in movable environments such as blood, a lymphatic fluid or a liquid culture medium have characteristics in which they move (migrate) in response to a chemical stimulus which are caused by a chemical substance, a growth factor or the like. Cells also migrate in response to an electrical stimulus, a physical stimulus such as a contact stimulus, or other external factors in such environments. Research and development have been conducted on methods, a device, an instrument and a material used for the method, wherein a stimulus by which cell migration is promoted is selected and used to specifically identify and separate target cells from a heterogeneous cell group, with a focus on the moving capability of cells.
A plurality of research examples in which cell migration is controlled by cell chemotaxis in response to a chemical substance have been provided so far, and a cytologic diagnosis using chemotaxis has become practical as an application. As an exemplary method in which cells are separated and diagnosed using chemotaxis, there is a method using a Boyden chamber that is divided into upper and lower compartments separated by a porous filter. In this method, a chemical substance for attracting specific cells is provided in the compartment below the filter of the Boyden chamber, and various cells are seeded in the compartment above the filter. Therefore, it is possible to observe the movement of cells in a direction of the compartment below the filter and to collect the cells that moved.
However, in the method of separating cells using chemotaxis, there is a risk in which, since cells are stimulated with a chemical substance or a growth factor, properties of cells such as differentiation, proliferation, and functional expression of target cells are influenced, and the properties of cells before and after stimulation may be changed. That is, since chemotaxis tends to destabilize properties of the target cells, use of chemotaxis is disadvantageous in a cell therapy or diagnosis in which stimulated cells are administered into a living body.
On the other hand, by providing a so-called scaffold formed of a suitable material such as silicon for cells, a method is proposed in which a difference of migration capabilities between cells that move on the scaffold is used to identify or separate the cells. For example, methods (Non-Patent document 1 and Non-Patent document 2) are reported in which, a migration direction of cells is controlled when cells are seeded on a substrate on which a regular pattern having a regular triangular prismatic shape of a micro order is formed on a silicon substrate using a photoresist technology or on a substrate having a surface on which protrusions are formed.
When cell migration is induced using the scaffold as a stimulant, properties of cells are less likely to be changed before and after stimulation unlike in chemotaxis. Accordingly, research on structural characteristics and properties of the scaffold, and a migration capability and a direction control of cells is proceeding.